The broad, long-term objectives of the proposed research are to describe and explain patterns of stability and change in alcohol use and problem drinking during the transition from adolescence to young adulthood. The proposed investigation will utilize the "Monitoring the Future" (Johnson, O'Malley & Bachman, 1989) longitudinal data on national samples of over 20,000 high school seniors and graduates to provide needed evidence regarding the developmental trajectories of alcohol use during the transition to young adulthood. The specific aims are: 1) to investigate stability and change in alcohol use across several points in time during the transition from adolescence to young adulthood within the general population; 2) to identify subgroups of drinkers according to common trajectories of stability and change in heavy drinking over time, and examine differences in drinking-related problems across the subgroups; and 3) to investigate stability and change in the "psychosocial context of alcohol use" (e.g., attitudes and values concerning alcohol use, peer use of alcohol), and examine its potential causal relationship to alcohol use during the transition to young adulthood. A variety of longitudinal analyses (e.g., structural equation modeling) will be used to examine the stability and change in the frequency, quantity, and psychosocial context of alcohol use across several biennial intervals between the senior year in high school and up to 14 years post-high school. Findings from this research will have important implications for the understanding of the epidemiology, prevention, and treatment of alcohol abuse.